It's normal to sweat when we're in situations that make us feel anxious, such as job interviews and first dates. They invoke our "fight or flight" response, which is what happens when the body decides that you'll soon need to move quickly to react to some kind of threat, either by confronting it or running away. Obviously, an interview or a date isn't an actual threat, but your nervous system doesn't know that. It sends a message to your sweat glands to produce perspiration so your body can remain cool (and slippery) during this supposedly dangerous encounter. Of course, if you're already feeling nervous, sweating will only make things worse because you'll start worrying about whether your sweat is noticeable to others.
Most of us just feel a little sweaty or get clammy hands when this happens, but some people experience extreme sweating because of social anxiety, social phobias or panic attacks. If your social sweating is accompanied by other physical symptoms such as shortness of breath or nausea, or you find yourself avoiding social situations, it may be more than just basic nervousness. The good news is that social anxiety can be treated effectively with behavioral therapy and antidepressants or anti-anxiety medications. You might also want to try meditation and breathing exercises.